Milan had lost their last nine matches against the Bianconeri, including last season's Coppa Italia final, but a rocket from 18-year-old midfielder Locatelli on 65 minutes proved enough to secure a first win over Juve since November 2012.

However, the outcome could have been different after a first-half free kick from Juventus midfielder Miralem Pjanic was controversially disallowed for what looked a tight offside call, having initially been given by the officials.

On the last play of the game, 17-year-old Milan keeper Gianluigi Donnarumma produced a brilliant fingertip save to turn over a long-range effort by Sami Khedira which looked destined for the top corner.

Juventus manager Massimiliano Allegri was forced to make a change on 33 minutes when Paulo Dybala pulled up, feeling the back of his thigh, whil Milan lost M'Baye Niang to an ankle injury after the goal.

Milan move up into second place, two points behind Juve and three ahead of Roma, who host Palermo on Sunday night.

Sampdoria claimed their first win in seven Serie A games with a 2-1 victory over local rivals Genoa at the Stadio Luigi Ferraris.

Luis Muriel gave the hosts an early lead before Luca Rigoni equalised after 24 minutes. Sampdoria were then awarded a penalty on the stroke of half time but Fabio Quagliarella saw his spot-kick saved by Mattia Perin.

But Genoa defender Armando Izzo scored an own-goal to hand Marco Giampaolo's side an all-important derby win